The purpose of this research is to improve the management of women who have genital HSV infections during pregnancy, of infants exposed to HSV and of infants infected with HSV. The clinical history of HSV recurrences during pregnancy will be compared with disease activity for an equivalent period before and after the pregnance to determine whether pregnancy increases the frequency or severity of recurrences. The incidence of asymptomatic shedding will be assessed in women with recent lesions and in those with few or no recurrences during pregnancy. Cervical cultures will be obtained from women with active lesions to determine the prevalence of cervical shedding associated with recurrences. Factors which may affect the risks for the infant will be studied including the antiviral properties of amniotic fluid and the amount of antibody that individual infants acquire transplacentally. The ability to predict the infant's HSV titer at birth from the mother's titer 4-8 weeks before delivery will be investigated. The studies of viral shedding and antibody will be analyzed to determine whether infants of women with HSV during pregnancy can be assigned to groups at low and high risk of infection so that C-section can be elected for those most likely to benefit. To assess the basis for the increased susceptibility of newborns to severe HSV, mechanisms by which the non-immune host restricts the cell to cell spread of HSV will be evaluated in vitro using an assay of plaque area reduction by antibody and non-immune leukocytes and macrophages. The acquisition of specific immunity by adults with primary infections and by newborns will be compared using assays of antibody producion, lymphocyte transformation, and leukocyte derived chemotactic factor production.